A. Field of the Invention
The present invention relates generally to the field of windshield wiper control systems and more particularly to a windshield wiper control system that provides a selectable and continuously variable delay interval between successive windshield wiper sweeps and that may be utilized in conjunction with a conventional wiper switch as provided by the manufacturer of an automobile with the conventional wiper switch operating independently of the variable delay windshield wiper control system.
B. Background of the Invention
Various windshield wiper control system arrangements of the prior art provide intermittent or variable speed operation of the windshield wiper system as provided by the manufacturer of an automobile. In these arrangements the speed of the windshield wipers or the delay time between successive wiper sweeps is varied under the control of an operator by the use of numerous electrical circuit arrangements.
A first type of windshield wiper control system that has a single wiper control switch and that utilizes a switching circuit in combination with a delay time circuit and a timing termination circuit is described in U.S. Pat. No. 3,492,558 which issued to R. K. Patterson, Jr. et al, on Jan. 27, 1970. This control system is effective to activate the switching circuit when the ignition switch is operated and to provide an initial sweep of the wipers when the single wiper control switch is activated. Thereafter, the timing circuit determines the delay time between successive operations or sweeps of the wipers as it charges up a timing termination circuit turns off the system after actuation of the wiper mechanism.
Another type of windshield wiper control system of the prior art described in U.S. Pat. No. 3,780,367 which issued to W. D. Holt on Dec. 18, 1973, utilizes a single wiper control switch, a variable delay timing circuit and a washer-initial sweep circuit. The single control switch is arranged to have positions corresponding to an off or nonoperating mode, a slow position, a fast position and an intermittent position. When the control switch is rotated from the off position to the intermittent position, a momentary contact is established to actuate the washer and the initial sweep circuit which includes a timing capacitor that produces several sweep operations of the wiper mechanism during the timing or discharge of the capacitor through a first relay in the washer-initial sweep circuit. As the control switch is fully rotated to the intermittent position, the delay timing circuitry utilizes a second timing capacitor and a second relay to produce successive sweeps spaced apart by a variable selectable delay interval. Both the delay timing circuitry and the initial sweep circuitry have adjustable controls to vary the number of initial sweeps and the delay time between successive sweeps in the intermittent position.
Other types of windshield wiper control circuits utilizing various types of time delay circuitry are described in the following U.S. Pat. Nos.: 3,581,178; 3,564,374, 3,219,901; 3,262,042, 3,353,079; 3,335,352; 3,364,410; and 3,483,459.
While the windshield wiper control arrangements of the prior art as discussed and referenced hereinabove are generally suitable for their intended purpose, they involve either complicated arrangements to provide initial operation of the wiper control system upon actuation in the intermittent or variable delay mode, or no provision for an immediate wiper sweep upon actuation of the wiper control system in the intermittent mode.
Further, the windshield wiper control systems of the prior art are not generally suitable for use in conjunction with the conventional wiper switch supplied by the manufacturer of the automobile. These prior art arrangements generally contemplate the replacement of the original equipment wiper control switch or the installation of the overall wiper control system as original equipment. Thus, the conventional wiper control switch provided as original equipment is not generally capable of operation independently of the intermittent wiper control system.